1,403 research outputs found
Gassmann Equivalence and Decompositions of Jacobians
No full textThis thesis deals with the concept of Gassmann equivalence and its application in obtaining isogenous and isomorphic products of Jacobians of algebraic curves.
We study Gassmann equivalent G-sets with a particular emphasis on rationally, locally integral and integrally Gassmann equivalent G-sets. We develop MAGMA functions that verify the only known example of transitive integral Gassmann equivalent G-sets due to Leonard L. Scott and could potentially be used to obtain new intransitive examples.
Our main results generalize theorems of D. Prasad and C. S. Rajan, D. Prasad and D. Arapura et al. In particular, we show that if C is an algebraic curve, G <= Aut(C) a finite group and X,Y rationally Gassmann equivalent G-sets then the Jacobians J[(C x X)/G] and J[(C x Y)/G] are isogenous. Moreover, if instead the G-sets X,Y are integrally Gassmann equivalent the above isogeny becomes an isomorphism
FIGURES 11–14 in Macrocnemis gracilis, a new genus and species of Idiocnemidinae (Zygoptera: Platycnemididae) from Papua New Guinea
No full textFIGURES 11–14. Macrocnemis gracilis, ligula (penis): 11) ventral; 12) lateral; 13) ventrolateral; 14) posterolateral. photos D. Gassmann/K. Ulmen.Published as part of Theischinger, G., Gassmann, D. & Richards, S. J., 2015, Macrocnemis gracilis, a new genus and species of Idiocnemidinae (Zygoptera: Platycnemididae) from Papua New Guinea, pp. 429-436 in Zootaxa 3990 (3) on page 434, DOI: 10.11646/zootaxa.3990.3.7, http://zenodo.org/record/24596
Macrocnemis Theischinger, Gassmann & Richards, 2015, gen. nov.
No full text<i>Macrocnemis</i> gen. nov. <p> <b>Etymology.</b> The generic name is a composite of <i>macro</i>, meaning large, and <i>cnemis</i>, meaning tibia (= shin), the basis of the name for several genera supposed to be close allies of the new genus.</p> <p> <b>Diagnostic characters.</b> Very large, long-bodied, narrow-winged damselfly, the male black with pale yellowish green thoracic and largely pale brownish-yellow abdominal markings, including two sets of lateral patches each on segments 3–7. Antennae in both sexes with relative length of first and second joints about 1:2. Posterior lobe of male pronotum upright, more or less rectangular with the top corners drawn out into tongue-like lobes. Female prothorax simple, posterior lobe laterally protruded. Ac located approximately mid-way between levels of Ax1 and Ax2. Quadrilateral widening distally, that of Fw with basal side approximately 1/2 as long as costal and distal side and 1/3 as long as posterior side, that of Hw with basal side 1/4–1/3 as long as costal side, approximately 2/3 as long as distal side and 1/5 as long as posterior side. Three cells between distal end of quadrilateral and level of subnodus. R4 arising a little before subnodus, IR3 at subnodus. Majority of cells in distal half of wings (between R2 and R4) squarish. Distal margin of wings weakly crenulated. Abdomen with S9 and S10 not significantly widened; markings largely pale brownish yellow and including two sets of lateral patches each on segments 3–7. Male with cerci almost as long as, and stouter than, the simple slender paraprocts. Ligula simple, with a pair of medium-sized apical lobes. Ovipositor valvae reaching slightly beyond end of abdomen, not surpassing cerci.</p>Published as part of <i>Theischinger, G., Gassmann, D. & Richards, S. J., 2015, Macrocnemis gracilis, a new genus and species of Idiocnemidinae (Zygoptera: Platycnemididae) from Papua New Guinea, pp. 429-436 in Zootaxa 3990 (3)</i> on page 430, DOI: 10.11646/zootaxa.3990.3.7, <a href="http://zenodo.org/record/245965">http://zenodo.org/record/245965</a>
FIGURE 20 in Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae)
No full textFIGURE 20. Idiocnemis lakekamuenis sp. nov., ♀, Lakekamu, prothorax in dorsal view, SEM.Published as part of Gassmann, Dirk & Richards, Stephen J., 2019, Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae), pp. 121-140 in Zootaxa 4560 (1) on page 135, DOI: 10.11646/zootaxa.4560.1.6, http://zenodo.org/record/262742
Idiocnemis lakekamuensis Gassmann & Richards 2019, sp. nov.
No full textIdiocnemis lakekamuensis sp. nov. (Figs 1, 3, 5, 9, 11, 14, 16–17, 20–21, 24 –25, 28) urn:lsid:zoobank.org:act: E6CCE2B9-ECA7-4445-B1CE-3 D74038 C3370 Holotype. ♂ Papua New Guinea, Gulf Province, Lakekamu Basin: 1 km south of Ivimka Camp (Camp coordinates: 146 ° 29.761'E, 7 ° 44.117'S, ~ 120 m a.s.l.), adjacent to seepage, 24.xi.1996 (field envelope no. 21(1)) (SAMA 07-001510). Deposited in the South Australian Museum. Paratypes. Papua New Guinea, Gulf Province, Lakekamu Basin. All specimens leg. S.J. Richards, collected from within ~ 1.5 km SSW of the following coordinates: 146 ° 29.761'E, 7 ° 44.117'S, at altitudes between 100–120 m a.s.l.: 1♂, ‘ 1 km transect’, south of Ivimka Camp, in forest, 22.xi.1996, field envelope no. 153 (ZFMK ODO 2018 / 1); 1♂, ridge trail, beside river, sitting on dry stick, 22.xi.1996, field no. 168 (SAMA 07-001511; 1♂, Ivimka Camp, 29.xi.1996, field no. 142 (SAMA 07-001512); 2♂♂, 1.5 km south of Ivimka Camp, 27.xi.1996, field no. 148 (SAMA 07-001513 – 4); 1♂, 500 m south of Ivimka Camp, perched in shade, 18.xi.1996, field no. 188 (RMNH); 1♀, approx. 500 m south of Ivimka Camp, on Bulldog Track, 20.xi.1996, field no. 145 (SAMA 07- 001515); 1♀, Bulldog Track, 1 km south to Ivimka Camp, 17.xi.1996, field no. 149 (SAMA 07-001516); 1♂, 1♀, site #4, garden, in flight near stream, 29.xi.1996, field no. 141 (SAMA 07-001517 – 18); 1♂, trickle along 1 km transect nr. Ivimka Camp, 24.xi.1996, [apps. lacking], field no. 167 (SAMA 07-001519); 1♂, Ivimka Camp, 24.xi.1996, field no. 21(2) (SAMA 07-001520); 1♂, Ivimka Camp, 29.xi.1996, field no. 184 (SAMA 07-001521); 1♂, 500 m southeast of Ivimka Camp, 16.xi.1996, field no. 156 (SAMA 07-001522); 1♂, Ivimka Camp, 27.xi.1996, field no.147 (SAMA 07-001523). Etymology. The species is named after the Lakekamu Basin in Papua New Guinea’s Gulf Province, the only location from where it has been recorded. Description of the holotype. Head. Labium dirty yellow, with median incision roughly arc-shaped. Labrum yellow-orange. Genae dark brown laterally, dirty yellow ventrally. Anteclypeus medium to dark brown; postclypeus brown-black. Frons and vertex, including antennal sockets, purple. Vertical black marking small, confined to area between ocelli, medially only slightly divided, posteriorly diverging, continuing laterally on occipital ridge from where it connects to black coloration of rear of head (Figs 1, 3). Thorax. Prothorax with median lobe only slightly convex in lateral view; posterior lobe roughly subrectangular in outline, posterior edge very slightly rounded; dorsum of prothorax black, diffusely limited against a yellow lateral area which extends onto mesostigmal plates; pleura with lower half black, except for a diffuse subtriangular intrusion originating from lateral bright marking which covers upper half of pleura. Synthorax (Fig. 5) with antehumeral stripe covering almost entire mesepisternum, dorsal carina marked with black; antehumeral stripe yellow-brown, with remnants of purple (probably original coloration). Metepisternum with posterior three-fourths covered by a purple bar which either completely (left side), or nearly (right side), encircles a semi-oval black spot in its middle, the latter forming a narrow connection to posterior part of black mesepisternal marking (on left side); anterior fourth of metepisternum dark black, distinctly limited against purple marking. Metepimeron with anterior part black except for a bright yellow stripe traversing its lower half horizontally and, posterior to the latter, a medium brown stripe which is somewhat bulged out posteriorly. Legs yellow-orange, joints and adjacent areas darkened. Underside of synthorax pale yellow, with a pair of black stripes. Wings. Hyaline. Arc inserting at or slightly distal (right HW) to Sn. R4 distal to Sn, less distinctly so in forewings. Pt rhombic, medium to dark brown. FW with 17 Px, HW with 15 Px. Abdomen. Ground colour medium to dark brown, with bright markings as follows (Fig. 1): S1 with a roughly half-circular dorsal purple marking, S2 with a sub-quadrangular but posteriorly widened purple marking, S3 with a yellow-orange basal dorsal spot and a subdistal ventral bright marking of same colour; S4 to 5 with bright markings similar to those in S3 but less distinct. S6 to 7 with no pale markings except for a very weak and diffuse yellow ventro-basal marking on S6. Slightly more than posterior dorsal half of S8 as well as entire dorsal surface of S9 with a greyish-brown (probably originally purple) marking, its corners rounded, anterior margin rather straight. Superior appendage with small subbasal process, apically rounded, and a subdistal almost finger-shaped subacute process which is longer than subbasal one (Figs 9, 11). Colour of appendages dark brown, inner tips pale yellow. Measurements holotype (mm). FW 21.5, HW 20.0; abdomen including appendages 31.5. Variation in males. Generally similar to the holotype. The metepisternal black spot within the purple bar can be either irregular or almost perfectly rectangular. In two specimens it is entirely enclosed by the bright mesepimeral marking on both sides of the synthorax. Measurements (mm). FW 20.0–22.5, HW 18.5–21.0 (n = 13); abdomen including appendages 29.5–33.5 (n = 9). Female (paratypes). Head. Labrum, genae and frons dirty-yellow, ante- and postclypeus intermingled with brown. Antennal segments dirty-yellow to orange-brown. Diffuse black vertical marking extends as a broad stripe between eyes, intermingled with some yellow around ocelli and antennae, continuing posteriorly in two black lines lateral to an orange stripe marking occipital ridge. In one specimen, black marking reduced to traces of black with largest portion of black centred around ocelli. Two pale turquoise subtriangular postocular spots present (original coloration probably faded) (Fig. 14). Rear of head yellow. Thorax. Prothorax with pronotum dark bluish-black, median pronotal lobe with a pair of diffuse black spots close to border with anterior lobe (Fig. 16). Posterior pronotal lobe subrectangular, posterior edge only very slightly bulged out medially (Figs 17, 20). Synthorax with colour pattern similar to male, but far less distinct. Mesepisternum with a diffuse pale yellow marking adjacent to anterior third of humeral suture and a weak yellow marking well before the suture’s posterior end; mesepisternum otherwise diffuse brownish, lacking clearly recognizable antehumeral stripes. Mesepimeron with anterior part black as in male, but with diffuse yellow markings at the areas where the male has its grey-purple markings. Metepisternum and metepimeron as in male, but less distinct. Wings. Pt asymmetric, anterior side distinctly longer than posterior side. Otherwise as in male. FW with 16–17 Px, HW with 13–14 Px. Abdomen. Ground colour black, with light markings as follows. S1 with pair of diffuse pale turquoise spots covering posterior two-third of dorsal surface, separated from each other except for a thin connection along border of S1 and S2. S2 with a pair of elongate pale yellow dorsal spots each roughly shaped as an asymmetric triangle. S3–7 dorsally with a distinct basal pale yellow spot and a smaller subdistal spot of same colour, both losing intensity towards posterior segments. S8–9 with a pair of large diffuse but (except for the teneral specimen from Bulldog Track [field no. 149]) distinctly separate pale yellow spots. S10 with a confluent pair of diffuse pale yellow spots, covering roughly posterior half of dorsal surface of that segment, isolating a black triangular marking on its anterior dorsal half. Cerci pale yellow (Figs 24, 25). Upper lateral part of valvae and tergite of S 8 pale yellow. Measurements (mm). FW 20.0–21.5, HW 19.0–20.0 (n=3); abdomen including valvae 27.5–29.5 (n=3). Differential diagnosis. The male of this species is readily identified by the colour pattern on its head. The central black marking on the vertex, which is subquadrangular in most members of the species group, is distinctly reduced to form a rather diffuse black area filling the space between the three ocelli. In only two other species, I. dagnyae Lieftinck, 1958, and I. mertoni Ris, 1913, is the black marking occasionally reduced as well, but never to such an extent as in I. lakekamuensis sp. nov. The male of the present species is also clearly distinguished from congeners by the shape of the superior appendage (Figs 9, 11) which is characterized by a short and pointed subbasal process and a hook-like, slightly pointed subdistal process. This arrangement is distinctly different from that in most other species of the Idiocnemis bidentata group where the subbasal process is shaped as a prominent subtriangular protrusion. Only I. pruinescens has a similarly shaped superior appendage; however, in that species the subbasal process is longer than in the present species, and rather blunt (cf. Gassmann 2000). The female of I. lakekamuensis sp. nov. can be recognized by its posterior pronotal lobe which has a characteristic subrectangular shape not similarly found in any other member of the species-group. The female’s head colour pattern is similar to that in I. inaequidens Lieftinck, 1932, I. schorri Gassmann, Richards & Polhemus, 2016, and the new species described below, in having the vertex of the head nearly entirely covered in black. The extent of the black marking, however, is less than in I. inaequidens and I. schorri, with the areas around the antennae left free of black, but the black coloration is more extensive than in the new species described below. Distribution and habitats. Southern Papua New Guinea (Fig. 28). Known only from the Lakekamu Basin in Gulf Province where I. lakekamuensis sp. nov. was found perched in sunlight on low vegetation along small, clearflowing seepages and streams in lowland rainforest. A detailed description of the vegetation, climate, fauna and flora of the type locality can be found in Mack (1998).Published as part of Gassmann, Dirk & Richards, Stephen J., 2019, Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae), pp. 121-140 in Zootaxa 4560 (1) on pages 122-128, DOI: 10.11646/zootaxa.4560.1.6, http://zenodo.org/record/262742
Macrocnemis gracilis, a new genus and species of Idiocnemidinae (Zygoptera: Platycnemididae) from Papua New Guinea
No full textTheischinger, G., Gassmann, D., Richards, S. J. (2015): Macrocnemis gracilis, a new genus and species of Idiocnemidinae (Zygoptera: Platycnemididae) from Papua New Guinea. Zootaxa 3990 (3): 429-436, DOI: 10.11646/zootaxa.3990.3.
FIGURE 13 in Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae)
No full textFIGURE 13. Idiocnemis milou sp. nov., Lakekamu: right superior appendage in dorso-lateral view, SEM.Published as part of Gassmann, Dirk & Richards, Stephen J., 2019, Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae), pp. 121-140 in Zootaxa 4560 (1) on page 131, DOI: 10.11646/zootaxa.4560.1.6, http://zenodo.org/record/262742
FIGURE 23 in Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae)
No full textFIGURE 23. Idiocnemis milou sp. nov., ♀, Lakekamu, posterior pronotal lobe in dorsal view, SEM.Published as part of Gassmann, Dirk & Richards, Stephen J., 2019, Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae), pp. 121-140 in Zootaxa 4560 (1) on page 136, DOI: 10.11646/zootaxa.4560.1.6, http://zenodo.org/record/262742
Idiocnemis milou Gassmann & Richards 2019, sp. nov.
No full text<i>Idiocnemis milou</i> sp. nov. <p>(Figs 2, 4, 6–8, 10, 13, 15, 18–19, 22–23, 26–28) urn:lsid:zoobank.org:act: 29502AED-F155-41A4-8348-65394A61C205</p> <p> <b>Holotype.</b> ♂ Papua New Guinea, Gulf Province, Lakekamu Basin: small creek ca. 1.5 km SSW of Ivimka Camp (Camp coordinates: 146 ° 29.761'E, 7 ° 44.117'S, 120 m a.s.l.), 25-xi-96, S.J. Richards leg. (SAMA 07-001524). Deposited in the South Australian Museum.</p> <p> <b>Paratypes</b>. Papua New Guinea, Gulf Province, Lakekamu Basin. All specimens leg. S.J. Richards, collected from within ~ 2 km SSW of the following coordinates: 146 ° 29.761'E, 7 ° 44.117'S, at altitudes between 100–120 m a.s.l.: 1♂, 1 km transect, 24.xi.1996, field no 185 (SAMA 07-001525); 1♂, Bulldog Track, 2 km south Ivimka Camp, 26.xi.1996, field no. 169 (SAMA 07-001526); 1♀, Bulldog Track, 1 km south of Ivimka Camp, 17.xi.1996, field no. 149 (SAMA 07-001527); 1♀, 1 km transect, south of Ivimka Camp, in forest, 22.xi.1996, field no. 153 (RMNH); 1♀, Bulldog Track, adjacent Ivimka Camp, 23.xi.1996, field no. 154 (SAMA 07-001528); 1♂, small stream, 1 km transect, 26.xi.1996, field no. 158 (SAMA 07-001529); 1♀, 1 km transect, south of Ivimka Camp, in forest, 22.xi.1996 (SAMA 07-001530); 1♂, along 1 km transect, south of Ivimka Camp, 25.xi.1996, field no. 23 (RMNH); 1♀, creek at end of ‘garden’ path, 300 m south of Ivimka Camp, 25.xi.1996, field no. 155 (SAMA 07-001531). Papua New Guinea, Gulf Province, Dark End Lumber (DEL) area, all specimens collected within a 500 m radius of the following coordinates: 07°08.894S, 144°22.937E, ~ 55 m a.s.l.: 1♂, west of DEL Camp, 4.00 p.m., next to pool in forest, 06.x.1999, field no. 130 (SAMA 07-001532); 1♂, field no. 85; 1♀, shady forest stream, adjacent DEL Camp, field no. 86 (ZFMK ODO 2018 /2); 1♂, in forest at ‘unlogged’ site, nr. DEL Camp, 4.30 p.m., in shade over small stream, field no. 131(ZFMK ODO 2018 /3); 1♂, small “seepage” at DEL Camp, in sun, 3.00 pm, 04.x.1999, field no. 87 (SAMA 07-001533); 1♂, 1♀, DEL Camp, 03.x.1999, field no. 136 (SAMA 07-001534 – 35).</p> <p> <b>Etymology.</b> It is a pleasure to name the new species after Mrs. Milout Martinot (Oegstgeest/ Netherlands), both in gratitude for her long-lasting personal friendship towards the first author, and in recognition of her engagement in civil initiatives for a more sustainable future. The name is placed as a noun by apposition.</p> <p> <b>Description of the holotype</b>. <i>Head</i>. Labium, except for reddish-brown end-hook, yellowish-brown. Mandibles and maxillae of same colour, except distal parts of mandibles reddish-brown. Labrum orange-brown, darkened at upper margin and on medio-basal depression. Ante- and postclypeus medium brown with traces of black. Entire dorsal surface of head including antennal sockets purple, except for a central black marking on vertex shaped as in Fig. 4. Antennal scapus black with distal pale yellow ring, pedicellus medium brown, flagellum medium brown. Central black marking continuing on rear of head, turning ventrally into a diffuse colour pattern of light and medium brown.</p> <p> <i>Thorax.</i> Prothorax with median lobe very slightly convex in lateral view; posterior pronotal lobe in dorsal view subtriangular but with lateral parts distinctly discontinued, lateral edges rectangular; posterior lobe not raised, in lateral view slightly bulgy except for posterior edge; prothorax dark brown to black, except for a diffuse pale yellow stripe reaching from lateral parts of anterior lobe across prothoracic pleura up to the mesostigmal laminae and areas more ventral to them. Synthorax (Fig. 6) dark brown to black with pale markings as follows: Mesepisternum with antehumeral purple stripes complete, evaginated halfway for nearly a third of entire course of stripe, this area black, which also covers dorsal carinal suture (Figs 6, 27). Metepisternum with a posterior squarish purple spot and a black area of same but slightly more irregular shape just anterior to it, the latter followed by a rather irregular purple rectangle covering roughly one fourth of metepisternum; all these pale markings connected ventrally (posteriorly) by a continuation of the pale marking that ends on mesepimeron in an irregular stripe. Anterior fourth of metepisternum deep black, bordered at its lower edge by a slightly diffuse but distinct pale yellow stripe. Metepimeron largely dark, except for a small diffuse pale yellow subtriangular spot at anterior upper corner; an even more diffuse pale yellow spot medially at lower margin. Underside of synthorax pale yellow anteriorly, pale orange posteriorly, with a pair of dark-brown stripes.</p> <p> <i>Wings</i>. Entirely hyaline. Ac inserts at Ab. Arc at Ax2 (forewings), slightly distal to Ax2 (hindwings). Pt rhombic, costal side very slightly longer than anal side, reddish-brown. FW with 16 Px (left) to 17 Px (right), HW with 15 Px.</p> <p> <i>Abdomen.</i> Largely medium brown to black, with pale markings as follows: S1 with a pair of roughly subtriangular purple spots. S2 with a pale pink dorsal marking shaped as an isosceles trapezoid widening distally, reaching from anterior end of segment to distinctly beyond halfway along segment. S3 to 6 with diffuse pale yellow-brown dorso-basal and subdistal markings (Fig. 2), the latter well defined against the dark brown rings that cover the posterior fifths of these segments; pale markings on S3 to 6 becoming less distinct posteriorly; S7 entirely dark, lacking bright dorsal markings; S8 with posterior half of dorsum and S9 with entire dorsum pink, with anterior dorsal edge of pink marking medially protruded at the level of dorsal carina; laterally, the marking reaches half way down the segments, edges roughly convex. Anal appendages in dorsal view strongly curved inwards; basal two-third of superior appendage comparatively straight in lateral view, apical part curved downwards. Superior appendage with large, basal protuberance shaped as an almost perfect right-angled triangle, slightly hooked apically; from the basal protuberance, a moderate inner shelf-like structure continuing distally bearing a subdistal spine-shaped process and in addition a smaller but distinct spine which is located between the subdistal process and the basal protuberance (Fig. 10). Inferior appendages robust and blunt apically, slightly curved upwards, about two-third the length of superiors. Appendages black, except for some diffuse orange-brown markings at inner sides and tips of superior ones, inner tubercle pale yellow.</p> <p>Measurements of holotype (mm). FW 22.0, HW 20.5; abdomen including appendages 31.5.</p> <p> <b>Variation in males.</b> The small spine between subbasal and subdistal process of superior appendage is lacking in some specimens (Fig. 13).</p> <p>Measurements (mm). FW 21.5–22.0, HW 20.5–21.0 (n = 4); abdomen including appendages 30.5–32.0 (n = 2).</p> <p> <b>Female</b> (paratypes). <i>Head</i>. Labium, maxilles and mandibles medium brown; the latter apically orange, with black tips. Labrum orange; ante- and postclypeus medium to dark brown; frons covered by a diffuse pale yellow stripe; its upper part, including antennal sockets, reddish-brown. Antennal scapus dark brown, the latter with pale yellow distal rings; pedicellus proximally and distally dark brown, medially light brown; flagellum dark brown. Posterior part of vertex, occiput and rear of head deep black, interrupted only by reddish-brown areas posterior to antennae as well as anterior and lateral to ocelli, by a pair of conspicuous pale yellow subtriangular postocellar spots (original coloration presumably faded) and a diffuse pale yellow stripe situated anteriorly and parallel to occipital ridge, isolated from postocular spots and protruding anteriorly between the posterior ocelli (Fig. 15).</p> <p> <b>FIGURE 25.</b> <i>Idiocnemis lakekamuensis</i> <b>sp. nov.,</b> ♀, Lakekamu, terminal abdominal segments in latero-dorsal view.</p> <p> <i>Thorax.</i> Prothorax with median lobe very slightly convex in lateral view; pronotum largely black-brown, pleura pale yellow. Anterior part of median lobe with a pair of slightly diffuse roundish to slightly oval black spots each covering a distinct depression of the median lobe (Fig. 18). Posterior pronotal lobe comparatively long, about same length as median lobe, not raised in lateral view, shaped as broadly rounded subtriangle with rather obtuse posterior edge and with lateral edges distinctly subrectangular; edge of posterior pronotal lobe broadly and clearly demarcated from its central part both in dorsal and lateral view, central part slightly bulgy (Figs 22, 23). Synthorax with coloration similar to male, but more diffuse and much paler. Anterior pale marking on metepisternum dorsally distinctly widened, the dark spot posterior to it narrowed dorsally. Underside of synthorax as in male.</p> <p> <i>Wings</i>. FW with 16 (right) to 17 (left) Px, HW with 15 Px (n=5). Arc distinctly distal to Ax2. Pt as in male but shape more equilateral. Otherwise as in holotype.</p> <p> <i>Abdomen</i>. Mainly black; similar to male, but with the following differences: S1 with a pair of subquadrangular whitish spots on dorsal half of segment; S2 with a dorsal elongate pale yellow marking which has its posterior corners extended into narrow stripes that extend halfway down the segment laterally. S3 to 7 with diffuse pale yellow markings, similar to male but less distinct. S8 to 10 each covered by a pale yellow marking dorsally, dorsal colour diffusely intermingled with black (S8), intruded by an anterior medial dark area (S9) or with an anterior half-circular black marking (S10); S 8 to 9 almost entirely covered by pale yellow in some specimens. Sternites of S8 dark brown to black, those of S9 yellow. Cerci yellow, their tips narrow, sharply pointed, darkened. Valvae with upper part yellow or with at least traces of yellow, lower part dark brown; visible part of ovipositor yellow. Styli medium to dark brown, apical parts yellowish.</p> <p>Measurements (mm). FW 21.0–23.0, HW 20.0–22.5 (n = 6); abdomen including valvae 29.0 (n = 3).</p> <p> <b>Differential diagnosis.</b> The new species, along with <i>I. lakekamuensis</i> <b>sp. nov.</b>, belongs to the smallest species of the <i>I. bidentata</i> species group and may be easily distinguished from all congeners by its thoracic colour pattern. The black dorsal synthoracic marking extends medially into the antehumeral stripes (Fig. 27), taking a roughly cross-shaped overall shape in dorsal view without, however, fully subdividing the latter as is the case in <i>I. nigriventris</i> Lieftinck, 1937 and <i>I. obliterata</i> Lieftinck, 1932. In lateral view, the colour pattern is characterized by the distinct bright mesepimeral marking showing two upper subrectangular offshoots, of which only the anterior one is in partial contact with the antehumeral stripe. This pattern most closely approaches that of <i>I. lakekamuensis</i> <b>sp. nov.</b> In that species, however, the anterior subrectangular element is fully in contact with the antehumeral stripe. The male superior appendage of <i>I. milou</i> <b>sp. nov.</b> is usually characterized by a small spine halfway between the subbasal and subdistal processes. A similar minute spine is present in <i>I. schorri</i>, but in that species the spine is situated close to the subbasal process (cf. Gassmann <i>et al</i>., 2016: figs 14a, b). In cases where the minute spine is lacking, the superior appendages of <i>I. milou</i> <b>sp. nov.</b> are reminiscent of those of <i>I. mertoni</i> (Fig. 12). However, both the subbasal and the subdistal process are more distinctly pointed in the new species.</p> <p> <b>Distribution and habitats.</b> Currently known only from Gulf Province in southern central New Guinea, between the Kikori River lowlands in the west and the Lakekamu Basin in the east. Like <i>I. lakekamuensis</i> <b>sp. nov.</b>, this species is closely associated with small, clear-flowing seepages and streams in lowland rainforest where it perches on low vegetation and twigs in patches of sunlight. A detailed description of the vegetation, climate, fauna and flora of the type locality can be found in Mack (1998).</p>Published as part of <i>Gassmann, Dirk & Richards, Stephen J., 2019, Two new damselflies of the genus Idiocnemis Selys from Gulf Province, Papua New Guinea (Odonata: Platycnemididae), pp. 121-140 in Zootaxa 4560 (1)</i> on pages 128-139, DOI: 10.11646/zootaxa.4560.1.6, <a href="http://zenodo.org/record/2627426">http://zenodo.org/record/2627426</a>
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